A cellular radio access network is a collection of cells that each includes at least one base station capable of transmitting and relaying signals to subscribers' wireless devices. A “cell” generally denotes a distinct area of a mobile network that utilizes a particular frequency or range of frequencies for transmission of data. A typical base station is a tower to which are affixed a number of antennas that transmit and receive the data over the particular frequency. Wireless devices, such as cellular or mobile phones, smart phones, camera phones, personal digital assistants (PDAs) and laptop computers, may initiate or otherwise transmit a signal at the designated frequency to the base station to initiate a call or data session and begin transmitting data.
Mobile service provider networks convert cellular signals, e.g., Time Division Multiple Access (TDMA) signals, Orthogonal Frequency-Division Multiplexing (OFDM) signals or Code Division Multiple Access (CDMA) signals, received at a base station from wireless devices into Internet Protocol (IP) packets for transmission within packet-based networks. A number of standards have been proposed to facilitate this conversion and transmission of cellular signals to IP packets, such as a general packet radio service (GPRS) standardized by the Global System for Mobile Communications (GSM) Association, an evolution of UMTS referred to as Long Term Evolution (LTE), mobile IP standardized by the Internet Engineering Task Force (IETF), as well as other standards proposed by the 3rd Generation Partnership Project (3GPP), 3rd Generation Partnership Project 2 (3GGP/2) and the Worldwide Interoperability for Microwave Access (WiMAX) forum.
A typical mobile service provider network, or mobile network, includes a core packet-switched network, a transport network, and one or more radio access networks. The core packet-switched network for the mobile network establishes logical connections, known as bearers, among the many service nodes on a path between a wireless device, attached to one of the radio access networks, and a packet data network (PDN). The service nodes then utilize the bearers to transport subscriber traffic exchanged between the wireless device and the PDN, which may include, for example, the Internet, an enterprise intranet, a layer 3 VPN, and a service provider's private network. Various PDNs provide a variety of packet-based data services to wireless devices to enable the wireless devices to exchange service data with application or other servers of the PDNs.
The increasing number and bandwidth requirements of services available to mobile devices pressures available mobile network resources. Policy and charging control (PCC) provides network operators with the means to manage service connections to ensure an efficient utilization of core, transport, and radio network resources. Different services, such as Internet, E-mail, voice, and multimedia, have different quality of service (QoS) requirements that, moreover, may vary by user. To manage service connections in a consistent manner for a mobile network that simultaneously carries multiple different services for multiple users, PCC provides a centralized control to determine an appropriate transport path for services, determine QoS requirements for the services, differentiate charging on a per-PCC rule basis, and determine resource allocation necessary to ensure QoS characteristics of transport paths sufficient to meet the QoS requirements for the various services.
In an LTE network, the PDN gateway device, or PGW implements a Policy and Charging Enforcement Function (PCEF) using packet filters to map Internet Protocol (IP) traffic onto respective bearers and/or to identify IP traffic for charging. Each bearer terminated by the PGW is associated with a PCC Rule that has one or more Traffic Flow Templates or traffic flow 5-tuples (e.g., IP source, IP destination, source port, destination port, protocol) that map the traffic to the bearer. While typically created upon establishing a new bearer, the PGW may modify a bearer rule while the bearer remains active to add or remove filters. For example, when a user requests a new service, the PGW may add filters corresponding to the service to the rule of the bearer that provides the required QoS characteristics for the service. The PGW may then map incoming service data traffic for the session to the bearer using the TFT and forward the service data traffic according to the bearer characteristics. Besides bearer identification, other filter actions may include packet drops, packet marking, and accounting, for example.
Filter definitions for requested services may be received by the PGW from a mobile device requesting services or from a device that implements a Policy Control and Charging Rules Function (PCRF). A PCRF sends filters to the PGW in the form of PCC rules that each includes a set of information, e.g., filters, enabling detection of a service data flow encompassing those packets associated with a session as well as parameters for policy control and/or changing control, such as QoS information. A PGW may designate a single bearer to carry traffic described by multiple such PCC rules that specify QoS information matching the QoS characteristics of the bearer. PCC rules dynamically provided by a PCRF response to service requests, for example, are “dynamic” PCC rules. In some cases, however, a network operator may statically configure PCC rules directly into the PCEF implemented by the PGW. Such PCC rules are referred to as “static” or “pre-defined” PCC rules.